Effects of combination of ACE inhibitor and angiotensin receptor blocker on cardiac remodeling, cardiac function, and survival in rat heart failure

Searching for Effective Treatments in HFpEF: Implications for Modeling the Disease in Rodents

BACKGROUND

While the prevalence of heart failure with preserved ejection fraction (HFpEF) has increased over the last two decades, there still remains a lack of effective treatment. A key therapeutic challenge is posed by the absence of animal models that accurately replicate the complexities of HFpEF. The present review summarizes the effects of a wide spectrum of therapeutic agents on HF.

METHODS

Two online databases were searched for studies; in total, 194 experimental protocols were analyzed following the PRISMA protocol.

RESULTS

A diverse range of models has been proposed for studying therapeutic interventions for HFpEF, with most being based on pressure overload and systemic hypertension. They have been used to evaluate more than 150 different substances including ARNIs, ARBs, HMGR inhibitors, SGLT-2 inhibitors and incretins. Existing preclinical studies have primarily focused on LV diastolic performance, and this has been significantly improved by a wide spectrum of candidate therapeutic agents. Few experiments have investigated the normalization of pulmonary congestion, exercise capacity, animal mortality, or certain molecular hallmarks of heart disease.

CONCLUSIONS

The development of comprehensive preclinical HFpEF models, with multi-organ system phenotyping and physiologic stress-based functional testing, is needed for more successful translation of preclinical research to clinical trials.

Silicate Ions Derived from Calcium Silicate Extract Decelerate Ang II-Induced Cardiac Remodeling

BACKGROUND

Pathological cardiac hypertrophy is one of the main activators of heart failure. Currently, no drug can completely reverse or inhibit the development of pathological cardiac hypertrophy. To this end, we proposed a silicate ion therapy based on extract derived from calcium silicate (CS) bioceramics for the treatment of angiotensin II (Ang II) induced cardiac hypertrophy.

METHODS

In this study, the Ang II induced cardiac hypertrophy mouse model was established, and the silicate ion extract was injected to mice intravenously. The cardiac function was evaluated by using a high-resolution Vevo 3100 small animal ultrasound imaging system. Wheat germ Agglutinin, Fluo4-AM staining and immunofluorescent staining was conducted to assess the cardiac hypertrophy, intracellular calcium and angiogenesis of heart tissue, respectively.

RESULTS

The in vitro results showed that silicate ions could inhibit the cell size of cardiomyocytes, reduce cardiac hypertrophic gene expression, including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC), decrease the content of intracellular calcium induced by Ang II. In vivo experiments in mice confirmed that intravenous injection of silicate ions could remarkably inhibit the cardiac hypertrophy and promote the formation of capillaries, further alleviating Ang II-induced cardiac function disorder.

CONCLUSION

This study demonstrated that the released silicate ions from CS possessed potential value as a novel therapeutic strategy of pathological cardiac hypertrophy, which provided a new insight for clinical trials.

Transcutaneous Vagus Nerve Stimulation Ameliorates the Phenotype of Heart Failure With Preserved Ejection Fraction Through Its Anti-Inflammatory Effects

BACKGROUND

A systemic proinflammatory state plays a central role in the development of heart failure with preserved ejection fraction (HFpEF). Low-level transcutaneous vagus nerve stimulation (LLTS) suppresses inflammation in animals and humans, mediated by an α7nAchR (alpha7 nicotinic acetylcholine receptor)-dependent pathway. We examined the effects of LLTS on cardiac function, inflammation, and fibrosis in the presence of α7nAchR pharmacological blockade in a rat model of HFpEF.

METHODS

Dahl salt-sensitive rats at 7 weeks of age were treated with high-salt diet for 6 weeks to induce HFpEF, followed by 4 weeks of (1) LLTS, (2) LLTS with the α7nAchR blocker methyllycaconitine, (3) sham, and (4) olmesartan. Blood pressure, cardiac function by echocardiography, heart rate variability, and serum cytokines were measured at 13 and 17 weeks of age. Cardiac fibrosis, inflammatory cell infiltration, and gene expression were determined at 17 weeks.

RESULTS

LLTS attenuated the increase in blood pressure; improved cardiac function; decreased inflammatory cytokines, macrophage infiltration, and fibrosis; and improved survival compared with other groups. Methyllycaconitine attenuated these effects, whereas olmesartan did not improve cardiac function or fibrosis despite maintaining similar blood pressure as LLTS. Heart rate variability was similarly improved in the LLTS and LLTS plus methyllycaconitine groups but remained low in the other groups. LLTS reversed the dysregulated inflammatory signaling pathways in HFpEF hearts.

CONCLUSIONS

Neuromodulation with LLTS improved cardiac function in a rat model of HFpEF through its anti-inflammatory and antifibrotic effects. These results provide the basis for further clinical trials in humans.

LKB1: An emerging therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are currently the most common cause of morbidity and mortality worldwide. Experimental studies suggest that liver kinase B1 (LKB1) plays an important role in the heart. Several studies have shown that cardiomyocyte-specific LKB1 deletion leads to hypertrophic cardiomyopathy, left ventricular contractile dysfunction, and an increased risk of atrial fibrillation. In addition, the cardioprotective effects of several medicines and natural compounds, including metformin, empagliflozin, bexarotene, and resveratrol, have been reported to be associated with LKB1 activity. LKB1 limits the size of the damaged myocardial area by modifying cellular metabolism, enhancing the antioxidant system, suppressing hypertrophic signals, and inducing mild autophagy, which are all primarily mediated by the AMP-activated protein kinase (AMPK) energy sensor. LKB1 also improves myocardial efficiency by modulating the function of contractile proteins, regulating the expression of electrical channels, and increasing vascular dilatation. Considering these properties, stimulation of LKB1 signaling offers a promising approach in the prevention and treatment of heart diseases.

Heart Angiotensin-Converting Enzyme and Angiotensin-Converting Enzyme 2 Gene Expression Associated With Male Sex and Salt-Sensitive Hypertension in the Dahl Rat

Angiotensin-converting enzyme 2 (ACE 2) in the heart including its sex dependency in the hypertensive heart, has not been much studied compared to ACE. In the present study, we used the Dahl salt-sensitive rat exposed to fructose and salt to model a hypertensive phenotype in males, females, and ovariectomized females. Blood pressure was measured by the tale-cuff technique in the conscious state. Expression of RAS-related genes ACE, ACE2, angiotensin II receptor type 1, Mas1, and CMA1 in the heart were quantified. The results revealed small but significant differences between male and female groups. The main results indicate the presence of a male preponderance for an increase in ACE and ACE2 gene expression. The results are in accordance with the role of androgens or male chromosomal complement in controlling the expression of the two ACE genes.

Cardiac fibrosis models using human induced pluripotent stem cell-derived cardiac tissues allow anti-fibrotic drug screening in vitro

Drug efficacy assessment without using animals is important for development of cardiac fibrosis treatment. In this study, potential anti-fibrotic drugs were screened in a model of diseased myocardium using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and non-CM in in vitro and in vivo heart failure models. Cardiomyogenic differentiation was induced in hiPSC to generate cardiac tissue, including both iPSC-CM and non-CM expressing fibroblast markers. Stimulation with TGF-β significantly increased cardiac fibrotic extracellular matrix (ECM) gene expression, and decreased cardiac contractile/relaxation velocity. Anti-fibrotic HGF significantly decreased fibrotic changes induced by TGF-β. A prostacyclin agonist, ONO-1301 (ONO), camostat mesilate (Cs), and pirfenidone (Pf) significantly decreased fibrotic ECM expression, and improved contraction/relaxation in the model stimulated with TGF-β. Consistent with the in vitro assay, the administration of ONO, Cs, or Pf for 8 weeks in J2N-k hamsters preserved the left ventricular ejection fraction and decreased cardiac fibrosis compared with the controls. The in vitro model simulating fibrotic cardiac tissue showed precise screening of anti-fibrotic drugs which indicated the expected therapeutic response in an in vivo heart failure model, suggesting that the in vitro model presented in this study is a useful tool for the screening of anti-fibrotic drugs.

Reversion of cardiovascular remodelling in renovascular hypertensive 2K-1C rats by renin-angiotensin system inhibitors

OBJECTIVES

Evaluate whether the RAS dual blockade would induce additional beneficial effects on cardiovascular remodelling when compared to monotherapy in renal hypertensive two kidneys-one clip (2K-1C) rats.

METHODS

Hypertensive 2K-1C and normotensive (2K) rats were treated for 14 days with submaximal doses of losartan (LOS), enalapril (ENA), losartan plus enalapril (LOS + ENA) or vehicle (water). Blood pressure and some parameters of cardiovascular remodelling were evaluated.

RESULTS

Systolic blood pressure (SBP) was higher in 2K-1C (209 ± 3 mm Hg, P < .05) than in 2K (113 ± 1 mm Hg) rats. There was an additional effect in 2K-1C treated with LOS + ENA (153 ± 9 mm Hg) on lowering SBP when compared to LOS (184 ± 12 mm Hg) or ENA (177 ± 9 mm Hg). None of the treatments had effect on SBP in 2K rats. In 2K-1C, cardiomyocyte hypertrophy was reduced by all treatments, although the cardiac hypertrophy indexes remained unchanged. 2K-1C aortas presented medial thickening that was partially reduced by the treatments. Intimal hyperplasia observed in 2K-1C (15.56 ± 0.89 µm vs 8.24 ± 0.80 µm) was reversed by ENA (9.52 ± 0.45 µm) or LOS + ENA (8.17 ± 0.53 µm). Collagen deposition was increased in 2K-1C hearts (1.77 ± 0.16 vs 1.28 ± 0.09) and aortas (8.1 ± 0.6 vs 5.2 ± 0.2). Treatment with LOS reduced (1.12 ± 0.14%) and ENA (0.81 ± 0.11%) or LOS + ENA (0.86 ± 0.11%) additionally diminished collagen only in 2K-1C hearts.

CONCLUSIONS

Submaximal doses of ACEi and/or ARB have inhibitory actions on cardiac remodelling and vascular hypertrophy not entirely dependent on their effects on blood pressure normalization in renovascular hypertensive rats. Combined therapy produced additional reduction in blood pressure than monotherapy despite a similar inhibition on cardiovascular remodelling.

Tongsaimai reverses the hypertension and left ventricular remolding caused by abdominal aortic constriction in rats

Treating ventricular remodeling continues to be a clinical challenge. Studies have shown that hypertension is one of the most common causes of ventricular remodeling, and is a major cause of cardiovascular risk in adults. Here, we report that Tongsaimai (TSM), a Chinese traditional medicine, could inhibit arterial pressure and left ventricular pressure to improve hemodynamic abnormalities in rats impaired by abdominal aortic constriction (AAC). Administration of TSM significantly reduced the heart mass index and the left ventricular mass index significantly in AAC rats. TSM could also markedly ameliorate cardiac collagen deposition and reduce the concentration of hydroxyproline in the heart of AAC rats. Moreover, TSM alleviated cardiac histomorphology injury resulting from AAC, including reducing cardiomyocyte hypertrophy, fibrous connective tissue hyperplasia, cardiomyocyte apoptosis, replacement fibrosis and the disorders of myocardial myofibrils, intercalated discs, mitochondria and mitochondrial crista. In addition, the levels of transforming growth factor (TGF) - β and inflammation-related molecules including tumor necrosis factor-α (TNF-α), which were over-expressed with AAC, were decreased by STM. In conclusion, STM could reverse the hypertension and left ventricular remolding caused by abdominal aortic constriction in rats.

Molecular Mechanisms Responsible for Diastolic Dysfunction in Diabetes Mellitus Patients

In diabetic patients, cardiomyopathy is an important cause of heart failure, but its pathophysiology has not been completely understood thus far. Myocardial hypertrophy and diastolic dysfunction have been considered the hallmarks of diabetic cardiomyopathy (DCM), while systolic function is affected in the latter stages of the disease. In this article we propose the potential pathophysiological mechanisms responsible for myocardial hypertrophy and increased myocardial stiffness leading to diastolic dysfunction in this specific entity. According to our model, increased myocardial stiffness results from both cellular and extracellular matrix stiffness as well as cell–matrix interactions. Increased intrinsic cardiomyocyte stiffness is probably the most important contributor to myocardial stiffness. It results from the impairment in cardiomyocyte cytoskeleton. Several other mechanisms, specifically affected by diabetes, seem to also be significantly involved in myocardial stiffening, i.e., impairment in the myocardial nitric oxide (NO) pathway, coronary microvascular dysfunction, increased inflammation and oxidative stress, and myocardial sodium glucose cotransporter-2 (SGLT-2)-mediated effects. Better understanding of the complex pathophysiology of DCM suggests the possible value of drugs targeting the listed mechanisms. Antidiabetic drugs, NO-stimulating agents, anti-inflammatory agents, and SGLT-2 inhibitors are emerging as potential treatment options for DCM.

Fucoidan⁻Fucoxanthin Ameliorated Cardiac Function via IRS1/GRB2/ SOS1, GSK3β/CREB Pathways and Metabolic Pathways in Senescent Mice

The effects of low molecular weight fucoidan (LMWF) in combination with high-stability fucoxanthin (HSFUCO) on cardiac function and the metabolic pathways of aging mice (Mus musculus) were investigated. We demonstrated that LMWF and HSFUCO could improve cardiac function in aging mice. Aging mice were treated with LMWF and HSFUCO, either on their own or in combination, on 28 consecutive days. Electrocardiography and whole-cell patch-clamp were used to measure QT interval and action potential duration (APD) of the subjects. Cardiac tissue morphology, reactive oxygen species, and Western blot were also applied. Ultra-high-performance liquid chromatography⁻quadrupole time-of-flight (UPLC-QTOF) mass spectrometry was used for investigating metabolic alterations. The use of LMWF and HSFUCO resulted in improvements in both ventricular rhythms (QT and APD). Treatment with fucoidan and fucoxanthin reduced the expression levels of SOS1 and GRB2 while increasing GSK3β, CREB and IRS1 proteins expression in the aging process. Three main metabolic pathways, namely the TCA cycle, glycolysis, and steroid hormone biosynthesis, were highly enriched in the pathway enrichment analysis. When taken together, the LMWF and HSFUCO treatment improved both the ventricular rhythm and the muscular function of aging subjects by interfering with the metabolism and gene function.

Efficacy of Topical Enalapril in Treatment of Hypertrophic Scars

BACKGROUND

Angiotensin II activation by angiotensin-converting enzyme (ACE) is a significant mediator in wound healing and collagen production. In this study, the effect of topical application of ACE on hypertrophic scar formation has been studied in a clinical trial.

METHODS

Thirty patients with hypertrophic scar and itching after treatment of 2^nd or 3^rd degree burns participated in this double-blinded clinical trial. Subjects had two same-degree scars on symmetrical sites of body which were randomly allocated into two groups. One side was treated with 1% enalapril ointment and the other side with placebo twice daily. During a 6-months follow-up, a scoring table for itching was completed on a daily basis by patients. Furthermore, a single surgeon measured size of scars once a month. The mean size, thickness and itching score were calculated for each scar and compared between medication and placebo-treated scars.

RESULTS

The mean size of scars in enalapril treated side was significantly less than scars in the placebo side. Additionally, enalapril treated scars had significantly lower itching scores compared to the placebo group.

CONCLUSION

Topical enalapril significantly decreases the clinical parameters of hypertrophic scar and also itching as an indirect indicative of scar improvement. Furthermore, enalapril proved to be clinically safe for patients with low incidence of adverse drug reactions and acceptable cost effectiveness.

Olmesartan attenuates pressure-overload- or post-infarction-induced cardiac remodeling in mice

Either angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor 1 blocker (ARB) attenuates cardiac remodeling. However, the overall molecular modulation of the reversing remodeling process in response to the ACEI or ARB treatment is not yet well determined. In this study, we examined whether gene expressions are modulated by ACEI (temocapril), ARB (olmesartan) or both in a murine model with transverse aortic constriction (TAC) and confirm whether periostin is a target gene of olmesartan in mice with myocardial infarction (MI). We detected 109 genes that were significantly up-regulated in TAC mice and a majority of these were down-regulated in response to temocapril, olmesartan or their combination which significantly attenuated cardiac remodeling at one or four weeks. Real-time RT-PCR demonstrated that olmesartan, temocapril or their combination down-regulated the expression of periostin. In MI mice treated with olmesartan for 4 weeks, the left ventricular end-diastolic and systolic dimensions measured with echocardiography were lower, whereas maximum rate of rise and fall rate of LV pressure (±dp/dt max) were greater, and Azan-staining cardiac fibrotic area was smaller. Furthermore, periostin was upregulated in response to MI, whereas olmesartan blocked this upregulation. Post-MI fibrosis was smaller in periostin knockout adult mice than in wildtype mice, while glycogen synthase kinase 3β was increased and cyclin D1 was decreased in periostin knockout mice. These findings indicate that periostin is a target gene of ARB and olmesartan reverses cardiac remodeling at least partially through the downregulation of periostin.

Integrated Treatment of Prostaglandin E1 and Angiotensin-Converting Enzyme Inhibitor in Diabetic Kidney Disease Rats: Possible Role of Antiapoptosis in Renal Tubular Epithelial Cells

To investigate the therapeutic mechanisms underlying prostaglandin E1 (PGE1) and angiotensin-converting enzyme inhibitor (ACEI) on reducing urinary protein in diabetic kidney disease (DKD). DKD rats were established and randomly divided into four groups: PGE1 (10 μg/kg/day) (P group), ACEI (10 mg/kg/day) (A group), combination of PGE1 with ACEI treatment (P + A group), and saline treatment group (DKD group). Untreated rats were used as normal control (N group). Urinary albumin, endothelin-1 (ET-1), angiotensin II (AngII), TUNEL assay, Masson's trichrome staining, and immunohistochemistry staining for CD68 were evaluated in all groups. Ten days after treatment, urinary albumin was significantly decreased in the P and P + A groups (p < 0.01 vs. the DKD group). At the end of 8 weeks, the albumin was still significantly reduced in the P + A group (p < 0.05 vs. the A group). ET-1 and AngII were also significantly decreased in three treatment groups (p < 0.01 vs. the DKD group), especially in the P + A group. Few cells underwent apoptosis in glomerular regions in DKD rats, while amounts of apoptotic cells were seen in tubules regions. Further, apoptosis and the areas of fibrosis in tubulointerstitial were both decreased most in the P + A group compared with the DKD group. Apoptosis of renal tubular epithelial cells may participate in the development and progression of DKD in rats. Combination of PGE1 with AGEI remarkably protects renal function compared with PGE1 or ACEI monotherapy. The potential therapeutic mechanisms of PGE1 and AGEI might be via multiple targets and, at least in part, through inhibiting the apoptosis of renal tubular epithelial cells.

Neurohormonal Blockade and Circulating Cardiovascular Biomarkers During Anthracycline Therapy in Breast Cancer Patients: Results From the PRADA (Prevention of Cardiac Dysfunction During Adjuvant Breast Cancer Therapy) Study

BACKGROUND

Anthracyclines are associated with cardiotoxic effects. Cardiovascular biomarkers may reflect myocardial injury, dysfunction, inflammation, and fibrosis and may precede and predict the development of left ventricular impairment. The aim of this study was to assess: (1) longitudinal change in circulating cardiovascular biomarkers, (2) the effect of metoprolol succinate and candesartan cilexetil on the biomarker response, and (3) the associations between on-treatment changes in biomarker concentrations and subsequent left ventricular dysfunction in patients with early breast cancer receiving anthracyclines.

METHODS AND RESULTS

This report encompasses 121 women included in the 2×2 factorial, placebo-controlled, double-blind PRADA (Prevention of Cardiac Dysfunction During Adjuvant Breast Cancer Therapy) trial with metoprolol and candesartan given concomitantly with anticancer therapy containing the anthracycline, epirubicin (total cumulative dose, 240-400 mg/m²). Cardiovascular magnetic resonance, echocardiography images, and circulating levels of biomarkers were obtained before and after anthracycline treatment. Cardiac troponins I and T, B-type natriuretic peptide, N-terminal pro-B-type natriuretic peptide, C-reactive protein, and galectin-3 increased during anthracycline therapy (all P<0.05). The troponin response was attenuated by metoprolol (P<0.05), but not candesartan. There was no association between change in biomarker concentrations and change in cardiac function during anthracycline therapy.

CONCLUSIONS

Treatment with contemporary anthracycline doses for early breast cancer is associated with increase in circulating cardiovascular biomarkers. This increase is, however, not associated with early decline in ventricular function. Beta-blockade may attenuate early myocardial injury, but whether this attenuation translates into reduced risk of developing ventricular dysfunction in the long term remains unclear.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrial.gov. Unique identifier: NCT01434134.

Renin angiotensin aldosterone inhibition in the treatment of cardiovascular disease

A collective century of discoveries establishes the importance of the renin angiotensin aldosterone system in maintaining blood pressure, fluid volume and electrolyte homeostasis via autocrine, paracrine and endocrine signaling. While research continues to yield new functions of angiotensin II and angiotensin-(1-7), the gap between basic research and clinical application of these new findings is widening. As data accumulates on the efficacy of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers as drugs of fundamental importance in the treatment of cardiovascular and renal disorders, it is becoming apparent that the achieved clinical benefits is suboptimal and surprisingly no different than what can be achieved with other therapeutic interventions. We discuss this issue and summarize new pathways and mechanisms effecting the synthesis and actions of angiotensin II. The presence of renin-independent non-canonical pathways for angiotensin II production are largely unaffected by agents inhibiting renin angiotensin system activity. Hence, new efforts should be directed to develop drugs that can effectively block the synthesis and/or action of intracellular angiotensin II. Improved drug penetration into cardiac or renal sites of disease, inhibiting chymase the primary angiotensin II forming enzyme in the human heart, and/or inhibiting angiotensinogen synthesis would all be more effective strategies to inhibit the system. Additionally, given the role of angiotensin II in the maintenance of renal homeostatic mechanisms, any new inhibitor should possess greater selectivity of targeting pathogenic angiotensin II signaling processes and thereby limit inappropriate inhibition.

Cardiac Protection of Valsartan on Juvenile Rats with Heart Failure by Inhibiting Activity of CaMKII via Attenuating Phosphorylation

Background. This study was undertaken to determine relative contributions of phosphorylation and oxidation to the increased activity of calcium/calmodulin-stimulated protein kinase II (CaMKII) in juveniles with cardiac myocyte dysfunction due to increased pressure overload. Methods. Juvenile rats underwent abdominal aortic constriction to induce heart failure. Four weeks after surgery, rats were then randomly divided into two groups: one group given valsartan (HF + Val) and the other group given placebo (HF + PBO). Simultaneously, the sham-operated rats were randomly given valsartan (Sham + Val) or placebo (Sham + PBO). After 4 weeks of treatment, Western blot analysis was employed to quantify CaMKII and relative calcium handling proteins (RyR2 and PLN) in all groups. Results. The deteriorated cardiac function was reversed by valsartan treatment. In ventricular muscle cells of group HF + PBO, Thr287 phosphorylation of CaMKII and S2808 phosphorylation of RyR2 and PLN were increased and S16 phosphorylation of PLN was decreased compared to the other groups, while Met281 oxidation was not significantly elevated. In addition, these changes in the expression of calcium handling proteins were ameliorated by valsartan administration. Conclusions. The phosphorylation of Thr286 is associated with the early activation of CaMKII rather than the oxidation of Met281.

Association of NPR3 polymorphism with risk of essential hypertension in a Chinese population

WHAT IS KNOWN AND OBJECTIVE

Essential hypertension (EH) is a common disease exhibiting large individual difference in occurrence, development and treatment response. Genetic factors are implicated in the development and progression of EH. This study aimed to explore the association between NPR3 single nucleotide polymorphism rs2270915 (A/G, Asn521Asp) and the risk of EH in a Chinese Han population by a case-control study.

METHODS

The study was a single-centre, case-control trial, in which a total of 287 EH patients and 289 age- and sex-matched healthy controls were enrolled. The inclusion criteria were as follows: Han Chinese origin, male or female patients, systolic blood pressure (SBP) ≥140 mm Hg and/or diastolic blood pressure (DBP) ≥90 mm Hg. The healthy controls were subjects without histories of cardiovascular or cerebrovascular diseases. NPR3 rs2270915 polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, primary human umbilical vein endothelial cells (HUVECs) were isolated from 19 fresh human umbilical cords and cultured. Atrial natriuretic peptide (ANP) concentration in cell medium was determined by enzyme-linked immunosorbent assay (ELISA). NPR3 mRNA expression was determined by real-time semi-quantitative PCR.

RESULTS AND DISCUSSION

No significant difference in genotype distribution of NPR3 rs2270915 polymorphism was observed between cases and controls (P>.05). Patients carrying the rs2270915 G allele showed decreased SBP, and the difference was marginal. As compared with cells carrying the rs2270915 AA genotype, those with the AG genotype showed significantly lower NPR3 mRNA expression levels (P<.05) and lower medium ANP concentration (P<.001).

WHAT IS NEW AND CONCLUSION

This study suggested that NPR3 rs2270915 polymorphism was associated with decreased SBP level marginally in EH patients in a Chinese Han population, and the polymorphism may function through decreasing NPR3 mRNA expression and ANP level.

Human Endomyocardial Biopsy Specimen-Derived Stromal Cells Modulate Angiotensin II-Induced Cardiac Remodeling

: Cardiac-derived adherent proliferating cells (CardAPs) are cells derived from human endomyocardial biopsy specimens; they share several properties with mesenchymal stromal cells. The aims of this study were to evaluate whether intramyocardial injection of CardAPs modulates cardiac fibrosis and hypertrophy in a mouse model of angiotensin II (Ang II)-induced systolic heart failure and to analyze underlying mechanisms. Intramyocardial application of 200,000 CardAPs improved left ventricular function. This was paralleled by a decline in left ventricular remodeling, as indicated by a reduction in cardiac fibrosis and hypertrophy. CardAPs reduced the ratio of the left ventricle to body weight and cardiac myosin expression (heavy chain), and decreased the Ang II-induced phosphorylation state of the cardiomyocyte hypertrophy mediators Akt, extracellular-signal regulated kinase (ERK) 1, and ERK2. In accordance with the antifibrotic and antihypertrophic effects of CardAPs shown in vivo, CardAP supplementation with cardiac fibroblasts decreased the Ang II-induced reactive oxygen species production, α-SMA expression, fibroblast proliferation, and collagen production. Coculture of CardAPs with HL-1 cardiomyocytes downregulated the Ang II-induced expression of myosin in HL-1. All antifibrotic and antihypertrophic features of CardAPs were mediated in a nitric oxide- and interleukin (IL)-10-dependent manner. Moreover, CardAPs induced a systemic immunomodulation, as indicated by a decrease in the activity of splenic mononuclear cells and an increase in splenic CD4CD25FoxP3, CD4-IL-10, and CD8-IL-10 T-regulatory cells in Ang II mice. Concomitantly, splenocytes from Ang II CardAPs mice induced less collagen in fibroblasts compared with splenocytes from Ang II mice. We conclude that CardAPs improve Ang II-induced cardiac remodeling involving antifibrotic and antihypertrophic effects via paracrine actions and immunomodulatory properties.

SIGNIFICANCE

Despite effective pharmacological treatment with angiotensin II type I receptor antagonists or angiotensin II-converting enzyme inhibitors, morbidity and mortality associated with heart failure are still substantial, prompting the search of novel therapeutic strategies. There is accumulating evidence supporting the use of cell therapy for cardiac repair. This study demonstrates that cells derived from human endomyocardial biopsies, cardiac-derived adherent proliferating cells (CardAPs), have the potential to reduce angiotensin II-induced cardiac remodeling and improve left ventricular function in angiotensin II mice. The mechanism involves antifibrotic and antihypertrophic effects via paracrine actions and immunomodulatory properties. These findings support the potential of CardAPs for the treatment of heart failure.

Cardiosphere-derived cells reverse heart failure with preserved ejection fraction (HFpEF) in rats by decreasing fibrosis and inflammation

The pathogenesis of heart failure with a preserved ejection fraction (HFpEF) is unclear. Myocardial fibrosis, inflammation, and cardiac hypertrophy have been suggested to contribute to the pathogenesis of HFpEF. Cardiosphere-derived cells (CDCs) are heart-derived cell products with antifibrotic and anti-inflammatory properties. This study tested whether rat CDCs were sufficient to decrease manifestations of HFpEF in hypertensive rats. Starting at 7 weeks of age, Dahl salt-sensitive rats were fed a high-salt diet for 6 to 7 weeks and randomized to receive intracoronary CDCs or placebo. Dahl rats fed normal chow served as controls. High-salt rats developed hypertension, left ventricular (LV) hypertrophy, and diastolic dysfunction, without impairment of ejection fraction. Four weeks after treatment, diastolic dysfunction resolved in CDC-treated rats but not in placebo. The improved LV relaxation was associated with lower LV end-diastolic pressure, decreased lung congestion, and enhanced survival in CDC-treated rats. Histology and echocardiography revealed no decrease in cardiac hypertrophy after CDC treatment, consistent with the finding of sustained, equally-elevated blood pressure in CDC- and placebo-treated rats. Nevertheless, CDC treatment decreased LV fibrosis and inflammatory infiltrates. Serum inflammatory cytokines were likewise decreased after CDC treatment. Whole-transcriptome analysis revealed that CDCs reversed changes in numerous transcripts associated with HFpEF, including many involved in inflammation and/or fibrosis. These studies suggest that CDCs normalized LV relaxation and LV diastolic pressure while improving survival in a rat model of HFpEF. The benefits of CDCs occurred despite persistent hypertension and cardiac hypertrophy. By selectively reversing inflammation and fibrosis, CDCs may be beneficial in the treatment of HFpEF.

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The pathogenesis of heart failure with a preserved ejection fraction (HFpEF) is unclear.

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Cardiosphere-derived cells (CDCs) are heart-derived cell products with antifibrotic and anti-inflammatory properties, which have been implicated in HFpEF.

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Dahl salt-sensitive rats were fed a high-salt diet for 6 to7 weeks and randomized to receive intracoronary CDCs or placebo.

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Following CDC treatment, diastolic dysfunction resolved in treated rats but not in the placebo group. Treatment with CDCs also lower LV end-diastolic pressure, decrease lung congestion, and enhance survival.

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CDC treatment decreased LV fibrosis and inflammatory infiltrates, and reversed many of the transcriptomic changes associated with HFpEF, but had no effect on cardiac hypertrophy.

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By selectively reversing inflammation and fibrosis, CDCs may be beneficial in the treatment of HFpEF.

Angiotensin II is required to induce exaggerated salt sensitivity in Dahl rats exposed to maternal separation

We previously reported that maternal separation, rat model of early life stress, enhances pressor responses to acute and chronic stressors. The aims of this study were to determine whether Dahl salt-sensitive (DS) rats subjected to maternal separation (MatSep-DS) as compared to normally reared DS (Ctl-DS) rats show exaggerated blood pressure responses to acute behavioral stressors, such as restraint stress or air jet stress (AJS), or, hypertensive stimuli including chronic high-salt diet (4% NaCl) and angiotensin II (AngII) infusion (200 ng/Kg/min) during 1 week. MatSep was performed in male DS rats for 3 h/day from postnatal days 2-14. At 8 weeks of age, rats were implanted with telemetry transmitters and allowed to recover. Mean arterial pressure (MAP) was not different between MatSep-DS and Ctl-DS rats at baseline (120 ± 2 mmHg vs. 118 ± 1 mmHg, n = 4-8). Blood pressure responses during AJS and restraint stress were not different between MatSep-DS and Ctl-DS at 3 min. However, blood pressure recovery from AJS was significantly impaired in MatSep-DS rats compared to Ctl-DS rats (P < 0.05). 3-h stress-induced similar responses in MatSep and Ctl-DS rats. Chronic blood pressure responses to AngII infusion in rats fed a high-salt diet displayed enhanced MAP in MatSep-DS when compared with Ctl-DS rats (167 ± 5 mmHg vs. 152 ± 2 mmHg, pinteraction <0.05). However, MAP increased similarly in both groups in response to AngII infusion or high-salt diet separately. Renal parameters such as proteinuria, urine flow rate, and urine electrolytes were not different between groups in response to each treatment. In summary, salt sensitivity induces exaggerated blood pressor responses only in presence of AngII due to early life stress.

The Blocking on the Cathepsin B and Fibronectin Accumulation in Kidney Glomeruli of Diabetic Rats

Hyperglycemia results in the activation of tissue angiotensin II. Angiotensin II stimulates the synthesis of ECM proteins and causes a decrease activity of proteolytic enzymes. The aim of this study was to assess the impact of multilevel blocking of the RAAS, cathepsin B activity, and fibronectin accumulation in the glomerular in the rats diabetes model. Sixty male Wistar rats were initially included. Diabetes was induced by intravenous administration of streptozotocin. The animals were randomized to six groups of ten rats in group. Rats in the four groups were treated with inhibitors of the RAAS: enalapril (EN), losartan (LOS), enalapril plus losartan (EN + LOS), and spironolactone (SPIR); another group received dihydralazine (DIH) and the diabetic rats (DM) did not receive any drug. After six weeks, we evaluated blood pressure, 24 h urine collection, and blood for biochemical parameters and kidneys. In this study, fluorometric, ELISA, and immunohistochemical methods were used. Administration of EN + LOS increased activity of cathepsin B in homogenates of glomeruli compared to DM. Losartan treatment resulted in reduction of the ratio kidney weight/body weight compared to untreated diabetic rats. SPIR resulted in the increase activity of cathepsin B in the homogenate of glomeruli. The values of cathepsin B in the plasma of rats in all studied groups were similar and showed no tendency.

DPP-4 inhibitor linagliptin ameliorates cardiovascular injury in salt-sensitive hypertensive rats independently of blood glucose and blood pressure

Background

It remains to be elucidated whether dipeptidylpeptidase-4 (DPP-4) inhibitor can ameliorate cardiovascular injury in salt-sensitive hypertension. The present study was undertaken to test our hypothesis that linagliptin, a DPP-4 inhibitor, administration initiated after onset of hypertension and cardiac hypertrophy can ameliorate cardiovascular injury in Dahl salt-sensitive hypertensive rats (DS rats).

Methods

High-salt loaded DS rats with established hypertension and cardiac hypertrophy were divided into two groups, and were orally given (1) vehicle or (2) linagliptin (3 mg/kg/day) once a day for 4 weeks, and cardiovascular protective effects of linagliptin in DS rats were evaluated.

Results

Linagliptin did not significantly affect blood pressure and blood glucose levels in DS rats. Linagliptin significantly lessened cardiac hypertrophy in DS rats, as estimated by cardiac weight and echocardiographic parameters. Linagliptin significantly ameliorated cardiac fibrosis, cardiac macrophage infiltration, and coronary arterial remodeling in DS rats. Furthermore, linagliptin significantly mitigated the impairment of vascular function in DS rats, as shown by the improvement of acetylcholine-induced or sodium nitroprusside-induced vascular relaxation by linagliptin. These cardiovascular protective effects of linagliptin were associated with the attenuation of oxidative stress, NADPH oxidase subunits, p67^phox and p22 ^phox, and angiotensin-converting enzyme (ACE).

Conclusions

Our results provided the experimental evidence that linagliptin treatment initiated after the appearance of hypertension and cardiac hypertrophy protected against cardiovascular injury induced by salt-sensitive hypertension, independently of blood pressure and blood glucose. These beneficial effects of linagliptin seem to be attributed to the reduction of oxidative stress and ACE.

Retinoid X receptor agonists inhibit hypertension-induced myocardial hypertrophy by modulating LKB1/AMPK/p70S6K signaling pathway

BACKGROUND

Retinoid X receptor (RXR) has been demonstrated to play an important role in cardiac development and has been implicated in cardiovascular diseases. This study aimed to examine the effects of RXRα agonist bexarotene on pathological left ventricular hypertrophy (LVH) in a spontaneously hypertensive rat (SHR) model and the underlying mechanism.

METHODS

WKY rats served as controls. SHRs were randomized into 3 groups at the age of 4 weeks and were treated (once daily for 12 weeks) with either bexarotene (30 or 100mg/kg body weight) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Neonatal cardiomyocytes were treated with AngII (10(-7) mmol/L) with or without the indicated concentration of RXRα ligand 9-cis-RA. The protein abundances of β-actin, RXRα, LKB1, phospho-LKB1, AMPK, phospho-AMPK, P70S6K, phospho-P70S6K, ACE, and AT1 receptor were measured along with blood pressure, body weight and angiotensin II (Ang II) levels. The effects of LKB1 downregulation by LKB1 small, interfering RNA were examined.

RESULTS

Treatment of SHRs with bexarotene resulted in significant inhibition of LVH without eliminating hypertension. Immunoblot with heart tissue homogenates from SHRs revealed that bexarotene activated the LKB1/AMPK signaling pathway and inhibited p70S6K. However, the increased Ang II levels in SHR serum and heart tissue were not reduced by bexarotene treatment. Treatment of cardiomyocytes with Ang II resulted in significantly reduced LKB1/AMPK activity and increased p70S6K activity. 9-cis-RA antagonized Ang II-induced LKB1/AMPK and p70S6K activation changes in vitro.

CONCLUSIONS

RXR agonists prevent the inhibition of the LKB1/AMPK/p70S6K pathway and regulate protein synthesis to reduce LVH. This antihypertrophic effect of bexarotene is independent of blood pressure.

Prevention of remodeling in congestive heart failure due to myocardial infarction by blockade of the renin–angiotensin system

Ventricular remodeling subsequent to myocardial infarction (MI) is a complex process and is considered to be a major determinant of the clinical course of congestive heart failure (CHF). Emerging evidence suggests that activation of the renin-angiotensin system (RAS) plays an important role in post-MI ventricular remodeling; however, it is becoming clear that this is one of several neurohumoral systems that are activated in CHF. Blockade of RAS by angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists attenuates the ventricular dysfunction, but the effects of individual drugs in reducing the morbidity and mortality in CHF patients are variable. Furthermore, there is a difference of opinion as to the time of initiation of therapy with RAS blockers after the onset of MI. Since blockade of RAS partially improves cardiac function, it is suggested that a combination therapy involving RAS blockers (angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor antagonists) and agents that affect other neurohumoral systems may prove useful for improved treatment of CHF. Although activation of RAS has been shown to promote oxidative stress in experimental studies, the use of antioxidant therapy in CHF patients is controversial. Recent experimental studies have shown that ventricular remodeling in CHF is associated with remodeling of subcellular organelles such as sarcolemma, sarcoplasmic reticulum, myofibrils and extracellular matrix in terms of their molecular structure and composition. Since attenuation of remodeling in one and/or more subcellular organelles by different agents may prevent the progression of CHF, it is a challenge to develop specific drugs affecting molecular mechanisms associated with subcellular remodeling for the improved therapy of CHF.

Rodent models of heart failure: an updated review

Heart failure (HF) is one of the major health and economic burdens worldwide, and its prevalence is continuously increasing. The study of HF requires reliable animal models to study the chronic changes and pharmacologic interventions in myocardial structure and function and to follow its progression toward HF. Indeed, during the past 40 years, basic and translational scientists have used small animal models to understand the pathophysiology of HF and find more efficient ways of preventing and managing patients suffering from congestive HF (CHF). Each species and each animal model has advantages and disadvantages, and the choice of one model over another should take them into account for a good experimental design. The aim of this review is to describe and highlight the advantages and drawbacks of some commonly used HF rodents models, including both non-genetically and genetically engineered models, with a specific subchapter concerning diastolic HF models.

A validated RP-HPLC method for simultaneous determination of propranolol and valsartan in bulk drug and gel formulation

Objective:

A simple, precise, and stability indicating high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of propranolol hydrochloride and valsartan in pharmaceutical dosage form.

Materials and Methods:

The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on Hypersil ODS C-18 column (250*4.6 mm, i.d., 5 μm particle size) with isocratic flow with UV detector. The mobile phase at a flow rate of 1.0 mL/min consisted of acetonitrile, methanol, and 0.01 M disodium hydrogen phosphate (pH 3.5) in the ratio of 50:35:15 v/v.

Results:

A linear response was observed over the concentration range 5-50 μg/mL of propranolol and the concentration range 4-32 μg/mL of valsartan. Limit of detection and limit of quantitation for propranolol were 0.27 μg/mL and 0.85 μg/mL, and for valsartan were 0.45 μg/mL and 1.39 μg/mL, respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for linearity, accuracy, precision, specificity, robustness.

Conclusion:

The analysis concluded that the method was selective for simultaneous estimation of propranolol and valsartan can be potentially used for the estimation of these drugs in combined dosage form.

Ghrelin counteracts salt-induced hypertension via promoting diuresis and renal nitric oxide production in Dahl rats

Ghrelin is the endogenous ligand for the growth hormone-secretagogue receptor expressed in various tissues including the heart, blood vessels and kidney. This study sought to determine the effects of long-term treatment with ghrelin (10 nmol/kg, twice a day, intraperitoneally) on the hypertension induced by high salt (8.0% NaCl) diet in Dahl salt-sensitive hypertensive (DS) rats. Systolic blood pressure (SBP) was measured by a tail cuff method. During the treatment period for 3 weeks, high salt diet increased blood pressure compared to normal salt (0.3% NaCl) diet, and this hypertension was partly but significantly (P<0.01) attenuated by simultaneous treatment with ghrelin. Ghrelin significantly increased urine volume and tended to increase urine Na⁺ excretion. Furthermore, ghrelin increased urine nitric oxide (NO) excretion and tended to increase renal neuronal nitric oxide synthase (nNOS) mRNA expression. Ghrelin did not alter the plasma angiotensin II level and renin activity, nor urine catecholamine levels. Furthermore, ghrelin prevented the high salt-induced increases in heart thickness and plasma ANP mRNA expression. These results demonstrate that long-term ghrelin treatment counteracts salt-induced hypertension in DS rats primarily through diuretic action associated with increased renal NO production, thereby exerting cardio-protective effects.

Novel mechanism of angiotensin II-induced cardiac injury in hypertensive rats: the critical role of ASK1 and VEGF

This study was undertaken to elucidate a novel mechanism underlying angiotensin II-induced cardiac injury, focusing on the role of oxidative stress and myocardial capillary density. Salt-loaded Dahl salt-sensitive hypertensive rats (DS rats), a useful model for hypertensive cardiac remodeling or heart failure, were orally given irbesartan (an AT1 receptor blocker), tempol (a superoxide dismutase mimetic) or hydralazine (a vasodilator). Irbesartan significantly ameliorated left ventricular ischemia and prevented the development of cardiac hypertrophy and fibrosis in DS rats. The benefits were associated with the attenuation of oxidative stress, normalization of myocardial capillary density and inhibition of capillary endothelial apoptosis. Moreover, DS rats with significant cardiac hypertrophy and fibrosis displayed decreased myocardial vascular endothelial growth factor (VEGF) expression and increased cardiac apoptosis signal-regulating kinase 1 (ASK1) activation. Treatment with irbesartan significantly reversed these phenotypes. Tempol treatment of DS rats mimicked all the above-mentioned effects of irbesartan, indicating the critical role of oxidative stress in cardiac injury. We also investigated the role of VEGF and ASK1 in oxidative stress-induced endothelial apoptosis by using cultured endothelial cells from wild-type and ASK1-deficient mice. Oxidative stress-induced ASK1 activation led to endothelial apoptosis, and VEGF treatment prevented oxidative stress-induced endothelial apoptosis by inhibiting ASK1 activation. We obtained the first evidence that oxidative stress-induced cardiac VEGF repression and ASK1 activation caused the enhancement of endothelial apoptosis and contributed to a decrease in myocardial capillary density. These effects resulted in angiotensin II-induced progression of cardiac injury.

Dietary fish oil preserves cardiac function in the hypertrophied rat heart

Regular fish or fish oil intake is associated with a low incidence of heart failure clinically, and fish oil-induced reduction in cardiac remodelling seen in hypertrophy models may contribute. We investigated whether improved cardiac energy efficiency in non-hypertrophied hearts translates into attenuation of cardiac dysfunction in hypertrophied hearts. Male Wistar rats (n 33) at 8 weeks of age were sham-operated or subjected to abdominal aortic stenosis to produce pressure-overload cardiac hypertrophy. Starting 3 weeks post-operatively to follow initiation of hypertrophy, rats were fed a diet containing 10 % olive oil (control) or 5 % fish oil (ROPUFA® 30 (17 % EPA, 10 % DHA))+5 % olive oil (FO diet). At 15 weeks post-operatively, ventricular haemodynamics and oxygen consumption were evaluated in the blood-perfused, isolated working heart. Resting and maximally stimulated cardiac output and external work were >60 % depressed in hypertrophied control hearts but this was prevented by FO feeding, without attenuating hypertrophy. Cardiac energy efficiency was lower in hypertrophy, but greater in FO hearts for any given cardiac mass. Coronary blood flow, restricted in hypertrophied control hearts, increased with increasing work in hypertrophied FO hearts, revealing a significant coronary vasodilator reserve. Pronounced cardiac dysfunction in hypertrophied hearts across low and high workloads, indicative of heart failure, was attenuated by FO feeding in association with membrane incorporation of n-3 PUFA, principally DHA. Dietary fish oil may offer a new approach to balancing the high oxygen demand and haemodynamic requirements of the failing hypertrophied heart independently of attenuating hypertrophy.

Eplerenone potentiates protective effects of amlodipine against cardiovascular injury in salt-sensitive hypertensive rats

The clinical value of the combination of amlodipine and eplerenone is unclear. This study was undertaken to test whether eplerenone potentiates the protective effects of amlodipine against hypertensive cardiovascular injury. Salt-loaded Dahl salt-sensitive hypertensive rats (DS rats) were given (1) vehicle, (2) an antihypertensive dose of amlodipine, (3) a non-antihypertensive dose of eplerenone or (4) combined amlodipine and eplerenone for 6 weeks, and the effects on cardiovascular injuries were compared. There was no significant difference among the four groups regarding plasma aldosterone, urine volume or urinary electrolytes. A subpressor dose of eplerenone markedly ameliorated vascular endothelial dysfunction, cardiac inflammation and fibrosis in DS rats to a similar degree as an antihypertensive dose of amlodipine. Addition of eplerenone to amlodipine, without affecting blood pressure, enhanced the improvement by amlodipine of vascular endothelial function, cardiac inflammation, fibrosis and diastolic dysfunction in DS rats. Additive beneficial effects of eplerenone were attributed to additive potentiation of eNOS and Akt phosphorylation and additive reduction of oxidative stress. Eplerenone significantly attenuated cardiovascular NADPH oxidase activity by reducing gp91(phox) upregulation and attenuated the upregulation of cardiovascular AT1 receptor, but amlodipine failed to affect them. Thus, the normalization by eplerenone of gp91(phox) and AT1 receptor upregulation seems to be at least partially responsible for the additive benefits of eplerenone in the prevention of hypertensive cardiovascular injury. The combination of amlodipine and eplerenone may be a promising therapeutic strategy for cardiovascular disease in salt-sensitive hypertension.

Mechanisms of novel cardioprotective functions of CCN2/CTGF in myocardial ischemia-reperfusion injury

CCN2/connective tissue growth factor (CTGF), a CCN family matricellular protein repressed in healthy hearts after birth, is induced in heart failure of various etiologies. Multiple cellular and biological functions have been assigned to CCN2/CTGF depending on cellular context. However, the functions and mechanisms of action of CCN2/CTGF in the heart as well as its roles in cardiac physiology and pathophysiology remain unknown. Transgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) were generated and compared with nontransgenic littermate control (NLC) mice. Tg-CTGF mice displayed slightly lower cardiac mass and inconspicuous increase of myocardial collagen compared with NLC mice but no evidence of contractile dysfunction. Analysis of the myocardial transcriptome by DNA microarray revealed activation of several distinct gene programs in Tg-CTGF hearts involved in cardioprotection and growth inhibition. Indeed, Tg-CTGF mice subjected to ischemia-reperfusion injury by in situ transient occlusion of the left anterior descending coronary artery in vivo displayed reduced vulnerability with markedly diminished infarct size. These findings were recapitulated in isolated hearts perfused with recombinant human (h)CTGF before the ischemia-reperfusion procedure. Consistently, Tg-CTGF hearts, as well as isolated adult cardiac myocytes exposed to recombinant hCTGF, displayed enhanced phosphorylation and activity of the Akt/p70S6 kinase/GSK-3β salvage kinase pathway and induction of several genes with reported cardioprotective functions. Inhibition of Akt activities also prevented the cardioprotective phenotype of hearts from Tg-CTGF mice. This report provides novel evidence that CTGF confers cardioprotection by salvage phosphokinase signaling leading to inhibition of GSK-3β activities, activation of phospho-SMAD2, and reprogramming of gene expression.

Enalapril decreases cardiac mass and fetal gene expression without affecting the expression of endothelin-1, transforming growth factor β-1, or cardiotrophin-1 in the healthy normotensive rat

Angiotensin II can induce cardiac hypertrophy by stimulating the release of growth factors. ACE inhibitors reduce angiotensin II levels and cardiac hypertrophy, but their effects on the healthy heart are largely unexplored. We hypothesized that ACE inhibition decreases left ventricular mass in normotensive animals and that this is associated with altered expression of cardiac fetal genes, growth factors, and endothelial nitric oxide synthase (eNOS). Wistar rats (n = 7 per group) were orally administered with enalapril twice daily for a total daily dose of 5 mg·kg–1·d–1 (ENAP5) or 15 mg·kg–1·d–1 (ENAP15) or vehicle. Systolic blood pressure was measured by the tail-cuff method. Left ventricular expression of cardiac myosin heavy chain-α (MYH6) and -β (MYH7), atrial natriuretic peptide (ANP), endothelin-1 (ET-1), transforming growth factor β-1 (TGFβ-1), cardiotrophin-1 (CT-1), and renal renin were examined by real-time PCR, and eNOS using Western blot. Blood pressure was decreased only in ENAP15 animals (p < 0.05 vs. Control), whereas left ventricular mass decreased after both doses of enalapril (p < 0.05 vs. Control). MYH7 and ANP were reduced in ENAP15, while no changes in ET-1, TGFβ-1, CT-1, and MYH6 mRNA or eNOS protein were observed. Renal renin dose-dependently increased after enalapril treatment. Enalapril significantly decreased left ventricular mass even after 1 week treatment in the normotensive rat. This was associated with a decreased expression of the fetal genes MYH7 and ANP, but not expression of ET-1, CT-1, or TGFβ-1.

Valsartan protects against ER stress-induced myocardial apoptosis via CHOP/Puma signaling pathway in streptozotocin-induced diabetic rats

Recently studies indicated that valsartan could prevent the progression of heart failure caused by diabetic cardiomyopathy (DCM), while the mechanisms were still poorly understood. The present study was designed to investigate whether valsartan could reduce the endoplasmic reticulum (ER) stress and DCM-induced cardiac remodeling. Our data has shown that valsartan can ameliorate ER stress-induced cardiac remodeling and myocardial apoptosis in DCM rats. By using of immunofluorescence and RT-PCR, valsartan has been found to play a protective role via down-regulating the expression of transcriptional induction of C/EBP homologous protein (CHOP) and p53 upregulated modulator of apoptosis (Puma), two crucial factors known to be implicated in the ER stress-induced myocardial apoptosis. And the expression level of Puma was closely related to CHOP. Thus, our experiment strongly suggests that the administration of valsartan can ameliorate the ER stress through blocking the activation of CHOP/Puma signaling pathway, which provides a new insight into the potential molecular mechanism of cardiomyocyte apoptosis.

Olmesartan, an AT1 antagonist, attenuates oxidative stress, endoplasmic reticulum stress and cardiac inflammatory mediators in rats with heart failure induced by experimental autoimmune myocarditis

Studies have demonstrated that angiotensin II has been involved in immune and inflammatory responses which might contribute to the pathogenesis of immune-mediated diseases. Recent evidence suggests that oxidative stress may play a role in myocarditis. Here, we investigated whether olmesartan, an AT(1)R antagonist protects against experimental autoimmune myocarditis (EAM) by suppression of oxidative stress, endoplasmic reticulum (ER) stress and inflammatory cytokines. EAM was induced in Lewis rats by immunization with porcine cardiac myosin, were divided into two groups and treated with either olmesartan (10 mg/kg/day) or vehicle for a period of 21 days. Myocardial functional parameters measured by hemodynamic and echocardiographic analyses were significantly improved by the treatment with olmesartan compared with those of vehicle-treated rats. Treatment with olmesartan attenuated the myocardial mRNA expressions of proinflammatory cytokines, [Interleukin (IL)-1β, monocyte chemoattractant protein-1, tumor necrosis factor-α and interferon-γ)] and the protein expression of tumor necrosis factor-α compared with that of vehicle-treated rats. Myocardial protein expressions of AT(1)R, NADPH oxidase subunits (p47phox, p67phox, gp91phox) and the expression of markers of oxidative stress (3-nitrotyrosine and 4-hydroxy-2-nonenal), and the cardiac apoptosis were also significantly decreased by the treatment with olmesartan compared with those of vehicle-treated rats. Furthermore, olmesartan treatment down-regulated the myocardial expressions of glucose regulated protein-78, growth arrest and DNA damage-inducible gene, caspase-12, phospho-p38 mitogen-activated protein kinase (MAPK) and phospho-JNK. These findings suggest that olmesartan protects against EAM in rats, at least in part via suppression of oxidative stress, ER stress and inflammatory cytokines.

Clinical features of the dilated phase of hypertrophic cardiomyopathy in comparison with those of dilated cardiomyopathy

BACKGROUND

Although the dilated phase of hypertrophic cardiomyopathy (D-HCM) characterized by left ventricular (LV) systolic dysfunction and cavity dilatation has been reported to be a poor prognosis, this is now in contrast to the improved prognosis of dilated cardiomyopathy (DCM) in the era of advancements in heart failure management. There has been no investigation of the clinical features of D-HCM compared with those of DCM from the point of management of systolic dysfunction.

HYPOTHESIS

The aim of this study was to investigate the clinical features of D-HCM in comparison with those of DCM in a single institute.

METHODS

We studied 20 consecutive patients with D-HCM (global ejection fraction < 50%) and 115 consecutive patients with DCM.

RESULTS

At diagnosis of D-HCM, 8 (40%) of the D-HCM patients already experienced dyspnea (New York Heart Association [NYHA] class >or= III). Left atrial diameter was larger and prevalence of atrial fibrillation was higher in the D-HCM group, although LV size was larger and LV ejection fraction was lower in the DCM group. During the follow-up period (4.0 years), 11 (55%) of the patients with D-HCM died. The 5-year survival rate from all-cause mortality including cardiac transplantation was 45.6% in patients with D-HCM vs 81.6% in patients with DCM (log-rank P = .0001).

CONCLUSIONS

Patients with D-HCM were more symptomatic at diagnosis, although LV dilatation and impaired fractional shortening seemed more severe in patients with DCM. The prognosis for D-HCM patients was worse than that for patients with DCM despite similar or even more intensive treatment for heart failure.

A randomized, double-blind, placebo-controlled study to determine the effects of valsartan on exercise time in patients with symptomatic heart failure with preserved ejection fraction

Aims

To determine whether valsartan improves treadmill exercise time, in patients with symptomatic heart failure with a preserved ejection fraction (HFPEF), compared with placebo.

Methods and results

In this multicentred, double-blind, 14-week study, patients were randomized to receive valsartan (V) 80 mg or placebo (P) once daily on top of background medications. The dose of valsartan was force-titrated up to 320 mg. A total of 152 patients were randomized (V = 70, P = 82). Most patients had well-controlled hypertension (V = 91.2%, P = 89.0%) (mean baseline systolic BP ∼130 mmHg) and >50% were receiving an angiotensin-converting enzyme inhibitor and/or beta-blocker (V = 57.4%, P = 54.9%). The mean ejection fraction at baseline was 70.48% in the placebo group (n = 64) and 71.52% in the valsartan group (n = 79). Valsartan had no significant effect on exercise time (primary variable), gas exchange variables, 6 min walk test distance, exertion-related symptoms, brain natriuretic peptide levels, echocardiographic parameters, or quality-of-life scores. Valsartan significantly lowered peak exercise systolic BP (−13.1 mmHg vs. placebo; P < 0.001) and improved ratings of perceived exertion (Borg score) (−0.69 vs. placebo; P = 0.008).

Conclusion

In this population, which predominantly included patients with well-controlled hypertension and symptomatic HFPEF, addition of valsartan did not increase exercise time within 14 weeks. However, valsartan 320 mg reduced blood pressure and improved symptoms of perceived exertion (Borg score) during exercise and was generally well-tolerated.

Mechanism of diastolic stiffening of the failing myocardium and its prevention by angiotensin receptor and calcium channel blockers

OBJECTIVE

To investigate the mechanism responsible for the increased cardiac stiffness associated with hypertensive heart failure in Dahl salt-sensitive (DS) rats and the effects of treatment with the combination of a calcium channel blocker [azelnidipine (AZE)] and angiotensin II type 1 receptor blocker [olmesartan (OLM)].

METHODS

DS rats fed a high-salt diet from 7 weeks of age were treated (or not) from 12 to 19 weeks of age with the vasodilator hydralazine, OLM plus AZE, or the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin. Rats fed a low-salt diet served as controls.

RESULTS

Treatment with OLM plus AZE attenuated changes in the expression of collagen isoforms and a decrease in the ratio of elastin to collagen in the left ventricle and prevented the increase in myocardial stiffness and diastolic dysfunction in DS rats in a manner independent of the hypotensive effect of these drugs. Such treatment also inhibited the expression and activation of elastolytic proteases (including cathepsins S and K and metalloproteinases-2, -9, and -12), NADPH oxidase-dependent superoxide production, and inflammatory changes in the failing myocardium. All these effects were mimicked by treatment with apocynin.

CONCLUSIONS

The changes in collagen isoform expression and the decrease in the elastin to collagen ratio in the failing myocardium likely account for the increase in diastolic stiffness in this model of hypertensive heart failure. Administration of angiotensin receptor and calcium channel blockers prevented these changes in a manner independent of the hypotensive effect of these drugs by inhibiting the increase in elastolytic activity induced by activation of NADPH oxidase.

Effect of valsartan on left ventricular anatomy and systolic function and aortic elasticity

The objective of the study was to examine the effect of a 6-month daily treatment with 160 mg valsartan, an angiotensin II receptor blocker, on the left ventricular systolic function and aortic elasticity of patients with type 2 diabetes mellitus (T2DM) and healthy subjects. This was a prospective, randomized, double-blind, placebo-controlled crossover study. Thirteen healthy control subjects and 11 patients with T2DM were enrolled in the study. Eight control subjects and 4 T2DM patients completed the study. Cardiovascular magnetic resonance was used to evaluate the effect of valsartan on the left ventricular function and aortic elasticity. At baseline, T2DM patients had increased left ventricular mass (P = .006) when compared with the healthy controls. In the T2DM patients, treatment with valsartan, in comparison with receiving placebo, resulted in a reduction of aortic radius (P = .026) and wall thickness (P = .032) of the ascending aorta. In the abdominal aorta, valsartan treatment, when compared with placebo treatment, reduced the arterial compliance (P = .014) in the T2DM patients. Valsartan treatment for 6 months decreased the diameter and wall thickness of the ascending aorta in patients with T2DM, but may decrease AC of the abdominal aorta.

Enhancement of the endothelial NO synthase attenuates experimental diastolic heart failure

BACKGROUND

Diastolic heart failure is a rising problem with a high incidence and similar mortality and morbidity compared to patients with systolic heart failure. Nevertheless, the underlying pathophysiology is still debated.

AIM

We investigated the effect of pharmacological enhancement of endothelial nitric oxide synthase (eNOS) on experimental diastolic heart failure (DHF).

METHODS

DHF was induced in 60 DAHL salt-sensitive rats by salt diet in 8-week-old animals. 30 were treated with the eNOS enhancer AVE3085 (DHFeNOS) and 30 with placebo (DHF). Rats with normal salt intake served as controls.

RESULTS AND CONCLUSION

Diastolic dysfunction with increased diastolic stiffness constant and increased left ventricular (LV) pressure was analyzed by invasive pressure-volume loop measurements in the DHF group compared to controls. Cardiac hypertrophy as indicated by LV mass measurements by echocardiography, and increased cardiac collagen content as measured by immunohistochemistry were associated with an increased activation state of calcineurin, AKT, ERK(1/2), but not JNK and p38 kinases. Titin isoforms were not altered in this model of DHF. Treatment with AVE3085 significantly increased eNOS mRNA and protein levels in the cardiac tissue and decreases NAD(P)H oxidase subunits p22phox and gp91phox. Diastolic dysfunction was attenuated and cardiac hypertrophy and fibrosis were improved in comparison with untreated DHF animals. This was associated with a normalized activation state of calcineurin, AKT and ERK(1/2). Therefore, we suggest that targeting the NO system might yield a future therapeutic aim for the treatment of DHF.

Candesartan-induced gene expression in five organs of stroke-prone spontaneously hypertensive rats

To test the functional consequences of blocking the local renin-angiotensin system (RAS), we investigated the effects of an angiotensin II type 1 receptor blocker (ARB), candesartan, on the systemic gene expression profile of five important organs (brain, heart, kidney, liver and adipose tissues) in the stroke-prone spontaneously hypertensive rat (SHRSP), an established model of essential hypertension and cardiovascular disorders, and its normotensive control, the Wistar Kyoto (WKY) rat. Rats were treated with candesartan (5 mg/kg/d) for 4 weeks from 12 to 16 weeks of age. DNA microarray technology was used to identify changes in gene expression. Four weeks of treatment with candesartan significantly lowered systolic blood pressure in male rats of both the SHRSP and the WKY strains (p<0.0005). Candesartan differentially modulated the gene expression profile in an organ-specific manner in male SHRSP; of the five organs tested, gene expression was most prominently altered in the hearts of SHRSP. In contrast, candesartan treatment exerted minimal or no significant effects on the gene expression profile of the corresponding organs of male WKY rats. The inter-strain differences in gene expression changes induced by candesartan were considered to be associated with both blood pressure-dependent and independent mechanisms. These results help to delineate the mechanisms that underlie the organ or tissue protection conferred by ARB at the levels of cellular biology and genomics in the context of the local RAS. Further studies are warranted to investigate not only individual genes of interest but also genetic "networks" that involve differential organ- or tissue-specific gene expression induced by the blockade of RAS in essential hypertension. Tokyo, Japan

Effects of enalapril and losartan in left ventricular remodeling after acute myocardial infarction: a possible mechanism of prevention of cardiac events by angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in high-risk myocardial infarction

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARB) have been shown to have a significant cardioprotective effect in high-risk patients after myocardial infarction (MI). However, there are few data on the effects of these drugs on left-ventricular (LV) remodeling after MI in Japanese patients.

METHODS AND RESULTS

We randomly assigned 100 patients with anterior-wall MI who had received reperfusion therapy to treatment with either enalapril (n=50) or losartan (n=50), and calculated the LV ejection fraction (LVEF) and LV end-diastolic volume index (LVEDVI) in these patients at baseline and after 6 months of treatment. While a significant increase in the LVEF as compared with that at the baseline was observed in both groups, no significant difference was found in the rate of change of this parameter between the two groups. However, inverse correlations were observed between the baseline LVEF and LVEDVI and also the rates of change of the two parameters, suggesting that the greater the compromise of the LV function at baseline, the greater the preventive effect of both classes of drugs on LV remodeling.

CONCLUSION

The results of this study suggest that neither enalapril nor losartan is superior to the other in terms of the effect on LV remodeling after MI in Japanese patients. In addition, the suppressive effect of both classes of drugs on LV remodeling was greater in patients with more extensive infarction and greater compromise of LV function at baseline.

Where does albuminuria come from in diabetic kidney disease?

The classic mechanism to explain albumin excretion in diabetes has been permeability defects in the glomerular filter. However, a new concept has emerged that albuminuria can be explained by the two major pathways the proximal tubular cell uses to process filtered albumin. Specifically, albumin permeability through the glomerular filter is only governed by size selectivity. Most of the filtered albumin is retrieved by the proximal tubular cell and returned to the peritubular blood supply. Albuminuria in the nephrotic range would arise from retrieval pathway dysfunction. The small quantities of filtered albumin that are not retrieved undergo obligatory lysosomal degradation before urinary excretion as small peptide fragments. This pathway is sensitive to metabolic factors responsible for hypertrophy and fibrosis, particularly molecules such as angiotensin II and transforming growth factor-beta1, whose production is stimulated by hyperglycemic environments. Dysfunction in this degradation pathway may lead to albuminuria below the nephrotic range.